The present invention relates to the field of waste water treatment and, more particularly, to treatment of waste water effluent from a septic tank prior to disposal.
Drainage fields for land application of septic tank waste water effluent have traditionally been constructed by digging trenches on land adjoining the septic tank. Filtering beds are created in these trenches by depositing a layer of filtering material in the bottom of the trenches. Conventional filtering material is rock, crushed stone gravel, sand, or a combination thereof. A network of perforated pipes is then connected to the septic tank and laid in the trenches on top of the filter bed. The waste water effluent from the septic tank is distributed through the network of perforated pipes and trickles onto and through the filter bed, where its nutrient content is reduced by microbial action. After passing through the filtering material, the waste water effluent percolates through and is absorbed by the soil surrounding and underlying the drain field trench. Such systems normally operate by gravity flow, however, it is common practice to connect a pump to the septic tank to aid in moving the waste water effluent from the septic tank and through the drainage field, particularly where required by the lay of the land.
Standard practices, however, suffer from severe disadvantages. For example, conventional drainage fields for septic tanks require the transportation of heavy materials, such as the stone, rock gravel or sand required for installing filtration beds. In addition, conventional drainage fields generally operate for years, however, when they become clogged or otherwise stop functioning as designed, they must be dug up and replaced. Replacement of the drainage field costs essentially as much as installing a completely new field, and perhaps more.
With the foregoing in mind, the present invention provides a sequential flow nitrification drain field for filtration treatment of waste water. The invention is suited for treatment of waste water, and especially waste water effluent from a septic tank. The invention provides a renewable drain field which may be left in place for an extended useful life, and which provides enhanced treatment of the waste water.
The invention discloses a sequential flow filtration chamber for treatment of waste water effluent from a septic tank. In contrast to a conventional filtration chamber, the sequential flow filtration chamber includes one or more partitions arranged so as to channel the waste water in a flow path through the chamber. Thus, the term xe2x80x9csequential flowxe2x80x9d refers to the progression of the waste water through the flow path wherein the waste water receives filtration treatment which is incremental in nature. The treatment is incremental, since the waste water generally traverses the complete flow path before being discharged from the chamber.
The chamber comprises an inlet positioned in fluid communication with the septic tank for receiving waste water into the chamber. A plurality of partitions is positioned within the chamber so as to define a substantially sequential flow path for the waste water to follow. A filter is positioned within the flow path for filtering the waste water flowing in the flow path. An outlet is positioned in fluid communication with the flow path for discharging filtered waste water from the chamber. The partitions may be arranged within the chamber so that the sequential flow path is substantially vertical, or substantially horizontal.
The chamber may further comprise a removable cover to thereby provide access to the interior of the chamber. The filter is preferably a removable filter to thereby allow for periodic replacement. The filter comprises a lightweight particulate material enclosed within a water permeable sleeve, which may be in the form of a mesh. The lightweight filtering material may comprise a material selected from expanded polystyrene, and rubber chips such as from ground up tires. The filter is substantially arranged to comprise particulate material graded in size along the flow path so as to have relatively larger particles positioned toward the inlet and relatively smaller particles positioned toward the outlet.
The invention further provides a sequential flow nitrification drain field for filtration treatment of waste water. The drain field comprises a source of waste water, and at least one sequential flow filtration chamber. Preferably, the source of waste water for such a drain field is a septic tank.
The drain field of the present invention may further comprise a plurality of sequential flow filtration chambers connected in fluid communication to the source of waste water. The drain field may also include a plurality of sequential flow filtration chambers connected to each other in serial fluid communication so as to form a chain of chambers to thereby provide substantially incremental filtration of the waste water before discharge from the drain field.
The drain field is preferably disposed with at least one sequential flow filtration chamber having a replaceable filter. Having such replaceable filters, the drain field may be easily renewed, and thereby provides a lifetime which greatly exceeds that of a conventional septic tank drain field.
The drain field may also include other components, such as a distribution box connected in fluid communication generally between the waste water source and the sequential flow filtration chamber. In addition, the drain field may further comprise a discharge box having an inlet connected in fluid communication with the outlet of the chamber for receiving filtered waste water, and an outlet for discharging filtered waste water from the drain field for final disposal. The discharge box may comprise a plurality of outlets for discharging filtered waste water. The filtered waste water may be directed to flow through the plurality of outlets of the discharge box into a final filter prior to being discharged. Final disposal of the treated wastewater may be by discharge for soil percolation, or by any other approved method.
The present invention also provides for a method of treating waste water effluent from a septic tank. The method comprises the step of filtering the waste water effluent from the septic tank by channeling the waste water through a flow path containing a plurality of filtering particles so as to sufficiently treat the waste water for discharge. The step of filtering may be performed a plurality of times before the waste water is discharged. In addition, the filtering step may include filtering particles graded in size so as to comprise relatively larger particles positioned toward a start of the flow path and relatively smaller particles positioned toward an end of the flow path. The method may include a flow path which is substantially vertical, or substantially horizontal, and which extends through a plurality of connected chambers.